Fibrous nonwoven materials and fibrous nonwoven composite materials are widely used as products, or as components of products because they can be manufactured inexpensively and made to have specific characteristics. One approach to making fibrous nonwoven composite materials has been to join different types of nonwoven materials in a laminate. For example, U.S. Pat. No. 3,676,242 issued Jul. 11, 1972 to Prentice describes a laminar structure produced by bonding a nonwoven mat of fibers to a plastic film. U.S. Pat. No. 3,837,995 issued Sep. 24, 1974 to Floden discloses multiple ply fibrous nonwoven materials which contain one or more layers of thermoplastic polymer fibers autogeneously bonded to one or more layers of larger diameter natural fibers.
Another approach has been to mix thermoplastic polymer fibers with one or more other types of fibrous material and/or particulates. The mixture is collected in the form of a fibrous nonwoven composite web and may be bonded or treated to provide a coherent nonwoven composite material that takes advantage of at least some of the properties of each component. For example, U.S. Pat. No. 4,100,324 issued Jul. 11, 1978 to Anderson et al. discloses a nonwoven fabric which is a generally uniform admixture of wood pulp and meltblown thermoplastic polymer fibers. U.S. Pat. No. 3,971,373 issued Jul. 27, 1976 to Braun discloses a nonwoven material which contains meltblown thermoplastic polymer fibers and discrete solid particles. According to that patent, the particles are uniformly dispersed and intermixed with the meltblown fibers in the nonwoven material. U.S. Pat. No. 4,429,001 issued Jan. 31, 1984 to Kolpin et al. discloses an absorbent sheet material which is a combination of meltblown thermoplastic polymer fibers and solid superabsorbent particles. The superabsorbent particles are disclosed as being uniformly dispersed and physically held within a web of the meltblown thermoplastic polymer fibers.
The integrity of laminate materials described above depends in part on the techniques used to join the layers of the laminate. One disadvantage is that some effective bonding techniques add expense to the laminate materials and complexity to the manufacturing processes.
Fibrous nonwoven composites which contain a generally uniform distribution of component materials can have disadvantages which are related to the arrangement of the components. In particular, uniform distribution of certain fibers and particulates may promote linting and/or particle shedding. Another disadvantage is that composites which contain large proportions of uniformly distributed particulates or small fibers (e.g., pulp) generally have less integrity because less strength is provided by the thermoplastic polymer fiber component. This phenomenon can be seen in poor abrasion resistance and tensile strength properties of generally homogeneous composites containing large proportions of pulp and/or particulates. This problem is particularly apparent when such a nonwoven composite is used to wipe liquids or as a moist wipe. However, since pulp and certain particulates are inexpensive and can provide useful properties, it is often highly desirable to incorporate large proportions of those materials in fibrous nonwoven composite structures.
Accordingly, there is a need for a fibrous nonwoven composite structure which is inexpensive but has good abrasion resistance, integrity and wet-strength characteristics. There is also a need for a fibrous nonwoven composite structure which has a high pulp content and is inexpensive but has good abrasion resistance, integrity and wet-strength characteristics.